Apparatus for recovering oil from oil-bearing minerals



April 1964 F. J. SANDERS 3,130,132

APPARATUS FOR RECOVERING OIL FROM OIL-BEARING MINERALS Filed NOV. 10,1958 FIG. I

O CARRYING GAS INVENTOR.

FREDERICK J. SANDERS BY A1; ORNEY United States Patent 3,130,132APPARATUS FGR RECOVERING GIL FROM OIL-BEARING MINERALS Frederick J.Sanders, Shaker Heights, Ohio, assignor to The Standard Oil Compmy,Cleveland, Ohio, a corporation of Ohio Filed Nov. 10, 1958, Ser. No.773,041 3 Claims. (Cl. 2027) This invention relates to a method andapparatus for recovering oil from oil-bearing minerals. In particular,the present invention relates to a retorting process and a suitableapparatus for conducting such a process for the recovery of valuablehydrocarbon products from tar sands, oil shales, and the like.

Large deposits of oil-bearing minerals such as tar sands and oil shalehave long been known to exist in the world and are found in greatabundance particularly in this country and in Canada. Such depositscontain tremendous reserves of oil which are of great commercialsignificance in light of the diminishing world oil pool reserves, aswell as of strategic importance since such deposits represent potentialdomestic source of petroleum products.

Due to the above considerations, there has been considerable interest indeveloping a commercially feasible process for recovering oil from suchoil-bearing deposits. Various operational schemes have been proposed inthe prior art to accomplish this objective and, in particular, retortingoperations have been given wide attention.

conceptually, the retorting of such oil-bearing solids is quite simple.Essentially it involves merely the step of heating the solids atsuiiiciently elevated temperatures to educt the oil and the step ofrecovering the products evolved. However, when it is desired to practicesuch operations commercially on oil-bearing deposits which typicallycontain only 10 to 20% of oil or oil-producing organic matter, it can bereadily seen what large quantities of solids that must be handled andheated to relatively high temperatures in order to obtain comparativelysmall quantities of valuable oil products.

Obviously, therefore, in order to gain economic feasibility, retortingoperations must be adapted to continuous operation so as to permit ahigh unit throughput or capacity. Furthermore, it is essential that theoperation be substantially self-supporting so far as heat requirementsare concerned, deriving, if possible, all the heat requirements by thedirect combustion of part of the hydrocarbons present on the oil-bearingminerals with only the consumption of a minimum of valuable liquid andvapor oil products.

These basic considerations have been met by retorting operations longknown in the prior art which suggest the recovery of oil products fromoil-bearing minerals by passing the solids downwardly as a compactmoving bed in countercurrent contact with hot gases rising from aninternal combustion zone maintained in the lower regions of the retortso that the product oil vapors, together with the gaseous products ofcombustion, are removed from the top of the vessel while oil-free solidsare removed at the bottom of the retorting vessel. This process,however, introduces other serious operational difliculties which makessuch a retorting operation largely unattractive for commerciallyremoving oil from tar sands or shale.

The oil present on tar sands is in its natural state but is found to bea very viscous oil, often with a kinematic viscosity in the range of 66to over 6,000 centistokes at 210 F. Hence, when tar sands are treated bythe aforedescribed process of the prior art, the oil, instead of beingreadily vaporized from the solids, tends to burn inplace so that thegaseous recovery from the top of the retorting vessel is substantiallylow value combustion products including only slight yields of productoil vapors. This in-place burning of the oil also gives rise to cokeformation on the mineral solids and increases the tendency of the solidsto bridge within the retorting vessel which interferes with continuousoperation of the process. Furthermore, if the combustion process of thisretorting operation is controlled to be less severe so that the oil isnot burned in-place on the solids, the oil on the particles near thecombustion zone will not undergo suflicient vis-breaking or cracking topermit the oil to permeate the compact bed of colder solids in theretort above the combustion zone so that oil products may be effectivelyrecovered from the upper regions of the retorting vessel.

Due to other operational difliculties, such a retorting process has alsoproved commercially unattractive for recovering oil from shale. It iswell known that shale does not contain oil per se but rather contains anorganic substance known as kerogen which, when heated at sufficientlyhigh temperatures, converts into oil. Therefore, when shale is treatedin the aforedescribed process of the prior art, the kerogen convertsinto an oil which in contradistinction to the viscous oil on tar sandsis readily vaporized so as to be displaced from the residual mineralsolids in the upward flowing stream of gases. However, with the practiceof such a processing scheme, it will be obvious that substantial amountsof the product oil vapors carried upward from the retorting zone Will becondensed during its contact with the incoming cold solids. These liquidproducts then flow by gravity downward in the retorting vessel towardthe combustion zone, whereupon such products will be revaporized andrise again toward the top of the bed where the condensing action againoccurs upon the cold solids. A refluxing condition is thereforedeveloped with such overhead product recovery; and since these oilproducts for the most part are quite unstable thermally, such constantrefiuxing causes uncontrolled thermal cracking with a consequent highloss in potential oil yield. The presence of this refluxing conditionalso increases the tendency of the solid particles to agglomerate withthe result that clinker-lug within the retorting and combustion zones isaggravated. Moreover, some other of the vaporized normally liquidhydrocarbons in contact with the cold solids condenses in the form of afog which is not precipitated on the cold solids and therefore emergesfrom the retort in suspension in the gaseous product. This lattercondition requires either that a substantial loss of liquid product beaccepted or that unsually elaborate recovery equipment be provided tocapture the suspended oil droplets. The prior art has recognized theseundesirable conditions associated with this method of retorting shaleand additional means have been suggested to remedy one or more of thesedifficulties. All such means involve either the introduction ofextraneous materials in the retort or apparatus modifications, all ofwhich either increase the cost of operation or make the operation moredifficult of control.

A major object of this invention, therefore, is to provide a retortingmethod and apparatus for recovering oil from oil-bearing minerals sothat the oil may be effectively removed from the solids and,furthermore, to avoid subjecting the product oil vapors to severerefluxing conditions with consequent overheating and loss in yield.Another object of this invention is to provide a retorting apparatus ofcompact and simple design adaptable to the continuous passage ofoil-bearing solids downward through the vessel, thereby attaining a highthroughput unit capacity. A still further object of this invention is toprovide a process for recovering oil from oil-bearing minerals that isself-supporting in heat requirements for retortation by utilizing directinternal combustion of part of the hydrocarbons present on such solidswithout appreciably aifecting the potential yield of valuable liquid andvapor oil products.

The above and other objects of the invention are accomplished by a novelretorting operation and apparatus in which such operation may besuitably conducted whereby the hydrocarbon products educted from theoil-bearing solids are removed downstream from the hot combustion zonein a direction concurrent to the moving bed of solids incontradistinction to the usual direction of removing such hydrocarbonproducts. It is therefore contemplated in accordance with this inventionto pass particulate oil-bearing solids downwardly by gravity as acompact moving bed through an elongated vertical vessel having acombustion zone maintained at a substantially fixed position in thelower regions of the retort wherein gaseous and liquid oil productsresulting from the heating of the solids in the area of the combustionzone are removed from the retort downstream from the combustion zone.This reverse flow is accomplished by introducing an oxygen-containinggas, most conveniently air, in a downward direction within the retort ata level above the combustion zone and at a distance sufiiciently remotefrom the topof the retort to facilitate the flow of gas downward andacross the combustion zone. The oxygencontaining gas therefore supportsthe combustion process in the combustion zone as well as forcing thegaseous products of combustion and the oil products evolved from thesolids immediately above the combustion zone downward from thecombustion zone through the residual mineral matter present below saidzone to be collected and removed by means of a product outlet conduit.It will be obvious, therefore, that the present method of retortationeliminates the operational difiiculties heretofore discussed attendantto the retorting schemes of the prior art applied for the recovery ofoil from tar sands or shale in which the hydrocarbon products are takenoverhead countercurrent to the solid moving bed.

A better understanding of the method and apparatus of this inventionwill be gained from the following detailed description, taken togetherwith the appended patent drawings, in which:

FIGURE 1 is an elevational view partly in section rep resenting aschematic arrangement of the apparatus for carrying out the invention;

FIGURE 2 is a partial vertical section of FIGURE 1 taken along line 22showing a detail of Various of the elements within the retorting vessel;

FIGURE 3 is .a transverse horizontal section taken along line 3 -3 ofFIGURE 1; and

FIGURE 4 is a transverse horizontal section taken along line 44 ofFIGURE 1.

Referring now to the drawings, the reference numeral 1 refers generallyto an elongated upright retorting vessel comprising a metal shell 2suitably insulated With a refractory'lining 3. A charge hopper 4 of anysuitable construction is disposed at the top of the retort and is soadapted as to maintain a continuous feed of solid material into the topof the retorting vessel 1. Theupper portion 5 of the retorting vessel 1is substantially cylindrical in shape with the wall diverging outwardlyin a downward direction to a maximum diameter for the vessel somewhatbelow the combustion zone of the unit so as to diminish the tendency ofbridging or agglomeration of the particles within the combustion zone.The lower portion 6 of the retorting vessel 1 forms a frustum of a coneand converges into a central opening 7 in which is disposed a suitablevalve means 8. The rate of flow of solids'through the retort will, ofcourse, be controlled by regulating the discharge of spent solids fromvalve 8 as will be described in greater detail hereinafter.

A series of conduits enter the retorting vessel 1 at various levels asshown in the drawings, extending horizontally across the unit. Theseconduits may be supported in any suitable manner within the retort, suchas being directly supported from the walls of theretort. At theuppermost level is the oxygen-containing gas conduit 9. In order toachieve a uniform distribution of gas Within the retort, conduit 9 isadapted with communicating circular tubes 10 which are arranged in acommon horizontal plane with conduit 9 and are provided with openings 11to supply gas in a downward direction. At a level lower in the retort isthe product outlet conduit 12 adapted with communicating circular tubes13. The topside of tubes 13 have slotted openings 14 to effect theremoval of combustion gases and products from the retort in a manner tobe described hereinafter.

Depending upon the size of the retorting vessel, conduits 9 and 12 eachmay be adapted with more or less than the two communicating circulartubes shown in the drawings. Furthermore, various other structuralarrangements associated with conduits 9 and 12 will occur to thoseskilled in the art for supplying and removing, respectively, fluids fromthe retorting unit; and, consequently, there is no intention of limitingthe invention to the exact details shown and described. It is onlyimportant that the structural arrangement associated with conduits 9 and12 will provide for a uniform distribution of oxygen-containing gas fromconduit 9 to the combustion zone and the even removal of products fromthe retort to the product outlet conduit 12.

Deflectors 15, which may conveniently be an angle bar positioned as aninverted V, is mounted above each of the tubes 13 and overlying thetubes 13 sufiioiently to provide an angle of repose for the solidsimmediately above tubes 13 to prevent the entrainment of granular solidparticles in the gases removed from the unit. Deflectors 15 may bemounted on tubes '13 in any suitable manner, such as by welding directlyto tubes 13 or, if desired,

deflectors #15 may be supported directly from the walls of the retort.

The level of conduit 9 in the retort is not critical. However, theposition of conduit 9 will be somewhat determined by the relationshipthat must be observed between the height of the retort bed over conduit9 to the distance in the retort between conduit 9 and conduit 12. For afixed distance between the level of conduit 9 and conduit 12, thepressure drop from conduit 9 to conduit 12 will be inverselyproportional to approximately the square of the distance from conduit 9to the top of the retort. It therefore becomes obvious that in order tohave the gases which are supplied through conduit 9 flowingsubstantially downward in the retort toward conduit 12, it is necessaryto maintain the height of the retort above conduit 9 several times thedistance between the levels of conduits 9 and 12. Consequently, in orderto supply sufiicient air in a downward direction within the retort forthe effective removal of products by conduit :12 without the need forexcessive pressures on the gas in conduit 9, it is desired to have thedistance between conduits 9 and 12 to the height of the retort aboveconduit 9 maintained in a ratio of at least U4 and preferably1:5 to 1:6.For example, if the retort height is to be 30 ft., conduit 9 would belocated at a level 22 ft. from the top of the retort and conduit 12would be located 26 ft. from the top of the retort so that the heightabove conduit 9 to the distance between conduit 9 and conduit 12 wouldbe in the ratio of 5.5 to 1. Of course, a ratio of these distances lessthan 1:4 can be used if for other reasons it is desired to have a retortof relatively short over-all length if a corresponding adjustment ofpressure on the oxygen-carrying gas supplied through conduit 9 is made.

Conduit 20 is positioned in the lowerportion 6 of the retortingvessel 1. Conduit 20 supplies a cooling medium to the retort and isadapted with communicating circular tube 21 having openings 22 so as tointroduce the cooling medium uniformly to this level in the retort.Deflector 23 is provided in the manner shown to protect the openings 22from being clogged by solids.

The introduction of a cooling medium is not to be considered necessaryfor the successful operation of this process or apparatus but isadvantageous in that the solids removed are more convenient to handle ina cool condition. Furthermore, when water is used as the cooling medium,the steam that is generated when the water contacts the hot solids ishelpful in forming a seal against product leakage into outlet pipe 7 andis very helpful in stripping residual oil from the solid particles.

The operation of the retort will now be described in particularreference to the processing of tar sands. At the start of the operation,let it be assumed that the retorting vessel -1 has been filled fromhopper 4 by gravity flow with tar sands crushed to a suitable particlesize and that star valve 8 is closed. Hopper 4 contains an additionalsupply of crushed tar sands particles so that once valve 8 is opened theparticles will pass continuously downward in an uninterrupted column.The size of the tar sands particles is not critical, but it is preferredthat the particles will pass a 2-inch mesh sieve while beingsubstantially free of silt and fines which might be entrained in theproduct gases and vapors leaving the retort. It may be desirable ininitially starting the operation of the unit to fill the lower portion 6of retorting vessel 1 with sand such as flint shot Ottawa ranging from20 to 50 mesh in particle size, and filling the balance of the unit withthe tar sands particles.

The retorting operation is started by igniting the hydrocarbons presenton a horizontal strata of tar sands particles extending across the unitimmediately above the level of conduit 9. To accomplish this, a mixtureof a combustible gas and air may be temporarily injected through conduit12 from conduit '16 and burned within the retort to heat thehydrocarbons to a temperature above their ignition temperature, which isapproximately SOD-600 When the combustion process is under way, thesupply of gas is stopped while the supply of air is continued throughconduit 12 to support combustion. As an alternate method of initiatingthe combustion process, an air-gas burner may be temporarily placedwithin the retort just above conduit 12 to again heat the hydrocarbonsacross this level of the retort to a temperature above their ignitiontemperature. When the combustion process is under way, the air-gasburner may then be removed from the side of the retort so as not tolater interfere with the sustained operation of the process and air istemporarily supplied through conduit 12 to support combustion.

The combustion zone thus created is permitted to move upward a shortdistance from the original ignition level. It is most desirable that thecombustion zone attains uniform depth across the bed as well as uniformtemperatures. Thermal indicators well known to the art may be positionedwithin the retorting vessel to observe the conditions of the combustionzone so it will be possible to adjust air flow rates as required toreach desired conditions within the unit.

When the combustion zone reaches a level at least onehalf the distancebetween the level of conduit 12 and the level of conduit 9 and has builtup a uniform temperature across the bed in the range of 650 to 1100 R,the temporary supply of mr through conduit 12 is stopped and a supply ofair is introduced through conduit 9. This supply of air may be preheatedif desired.

During the initial ignition period, the products of combustion moveupward in the retort and are cooled by the unheated particles above thecombustion zone. In this comparatively brief period of time, a smallband of oil contained on the particles above is displaced by such gasflow; and when the reverse flow of air from conduit 9 reaches this area,these liquid products, together with products of combustion, flowdownward in the retort toward product outlet conduit 12, and thecombustion process continues with relatively even temperaturesthroughout the combustion zone.

After the flow of air has been reversed, the temperature in thecombustion zone is continued in the range of 650 tollOO" F. forsustained operation. At temperatures below 650 F. the viscous oilpresent on the tar sands is not effectively removed from the mineralparticles. At temperatures substantially greater than 1100 F. thecombustion reaction progresses too vigorously and the oil burnsin-place, giving off substantially all combustion gases with very littleyields of valuable oil products.

Valve 8 is now opened and the rate of discharge of residual solids fromthe retort is regulated so as to maintain the level of the combustionzone constant for the continued operation of the unit, and the rate offeed of fresh particles to restoring vessel 1 from hopper 4 is equal tosaid rate of discharge.

It is desirable that no more oxygen be introduced by way of conduit 9than will be consumed in the reactions at the combustion zone. In thismanner, no further combustion of the oil products can occur while theseproducts pass downward in the retort toward conduit 12. Therefore, itwill be obvious that when using air as the oxygencontaining gas that ifthe rate of air supplied through conduit 9 to attain the desiredtemperaure level in the combustion zone is inadequate to etfectivelyforce the oil products and the combustion products to flow downwardly inthe retort, then some extra non-combustible gas such as nitrogen must beadded with the air to cause such a result.

The heat from the combustion zone is suificient to educt thehydrocarbons from the oil-bearing solids immediately above thecombustion zone as vapors and liquid. The actual distribution of productbetween the vapor and liquid states will depend in great part on thetemperature level maintained in the combustion zone. The products areforced across the combustion zone and pass downwardly in the retortthrough the residual solids to the open areas found around tubes 13 dueto deflectors 15. The liquid and vapor oil products entering these openareas are readily collected in tubes 13 by means of slots 14-, togetherwith the gaseous combustion products and steam which is rising from thelower portion of the retort. The products so entering tubes 13 arewithdrawn from the retorting vessel by means of conduit 12 into arecovery system forming no part of this invention where they are to becooled, condensed, and put in storage. The products, while passingthrough the residual solids below the combustion zone, do not cool orreunite to the solids in any appreciable degree since these solids arestill hot from leaving the combustion zone. A slight vacuum ofapproximately to 300 mm. may be placed on conduit 12 if desired tofacilitate the removal of the products and combustion gases therethroughto the recovery system.

The residual solids flowing below conduit 12 are cooled by theintroduction of water through conduit 20 and tube 22. The water isconverted to steam on the hot solids which forms a seal against vaporleakage into outlet pipe 7. Some of the steam produced rises upwardly inthe retort to be collected in tubes 13 and is quite helpful in strippingthe descending solids of residual oil products and forcing theseresidual products upwardly in the retort to where they are alsocollected by tubes 13 and removed from the retort by means of conduit12.

Although the method and apparatus described herein have beenparticularly directed to the recovery of valuable oil products from tarsands, the process may also be adapted with slight modifications whichwill be obvious to those skilled in the art for the recovery of oil fromoil shale or any like solid substance.

It is therefore to be understood that the above description is merelyillustrative of preferred embodiments of the invention, and henceLetters Patent is requested to cover these and such other variationswhich will remain within the spirit of the invention and the scope ofthe appended claims.

I claim:

1. In a retortin-g apparatus for recovering oil from oil-bearing mineralsol-ids, the combination of a closed vertical retorting vessel having asubstantially fixed combustion zone a confined area of said vessel, ahopper means at the top of said retorting vessel :for introducingcrushed solids into said retorting vessel, an independent first inletand first outlet conduit below said combustion zone for temporarilysupplying an oxygencontaining gas to said combustion zone, anindependent second inlet conduit above said combustion zone and downfrom the top of said retorting vessel equipped with a gas distributingmeans adapted to disperse an oxygen containing gas uniformly over thecross-section of the mass of solids in a downwardly direction acrosssaid combustion zone when said temporary supply or" oxygen-containinggas is discontinued through said first inlet conduit, said first outletconduit for withdrawing a stream of combustion products and educted oilproducts from said retorting vessel, the height of the top of saidretorting vessel above said second inlet conduit being maintained atseveral times the distance between said second inlet conduit and saidfirst inlet and first outlet conduit an independent inlet conduit belowsaid first outlet conduit for introducing water into the 'lower regionsof said retorting vessel uniformly over the cross-section of the mass ofsolids to cool oil-free solids after combustion thereof, and anindependent second outlet conduit in the bottom of said retorting Vesselfor removing said oil-free solids therefrom.

2. 'In a retorting apparatus for recovering oil from tar sandsparticles, the combination of a closed elongated vertical retortingvessel having a substantially fixed combustion zone within a confinedarea of said vessel, a hopper means at the top of said retorting vesselfor introducing crushed tar sands particles into said retorting vessel,an independent first inlet and first outlet conduit below saidcombustion zone for temporarily supplying an oxygen-containing gasupwardly in said retorting vessel to said combustion zone, anindependent second inlet conduit above said combustion zone and downfirom the top of said retorting vmsel equipped with a gas distributingmeans adapted to disperse an oxygen-containing gas uniformly over thecross-section of the mass of sol-ids in a downwardly direction acrosssaid combustion zone when said temporary supply of oxygen-containing gasis discontinued through said first inlet conduit, said first outletconduit below said combustion zone located at a distance from saidsecond inlet conduit no greater than one-fourth the distance from thetop of said retorting 'vessel to said second inlet conduit forwithdrawing a stream of combustion products and eduoted oil products, anindependent third inlet conduit situated below said first outlet conduitfor introducing water into the lower regions of said retorting vesseluniformly over the cross-section :of the mass of solids to cool oil-freesolids after combustion thereof, and an independent second outletconduit at the bottom of said retorting vessel for removing cooloil-free solids therefrom.

3. The apparatus according to claim 2 wherein the gas distributing meansis a set otf communicating circular tubes arranged in a commonhorizontal plane and provided with openings to supply gas in adownwardly direction.

References Cited in the file of this patent UNITED STATES PATENTS704,886 Larsen July 15, 1902 1,146,776 Wallmann July 13, 1915 1,178,391:Fieisher Apr. 4, 1916 1,469,628 Dundas et al. Oct. 2, 1923 1,536,696Wallace May 5, 1925 1,598,217 Odell Aug. 3-1, 1926 1,598,831 Trumble -nSept. 7, 1926 1,607,241 Davis et al. i Nov. 16, 1926 2,774,726 EichnaDec. 18, 1956

1. IN A RETORTING APPARATUS FOR RECOVERING OIL FROM OIL-BEARING MINERALSOLIDS, THE COMBINATION OF A CLOSED VERTICAL RETORTING VESSEL HAVING ASUBSTANTIALLY FIXED COMBUSTION ZONE WITHIN A CONFINED AREA OF SAIDVESSEL, A HOPPER MEANS AT THE TOP OF SAID RETORTING VESSEL FORINTRODUCING CRUSHED SOLIDS INTO SAID RETORTING VESSEL, AN INDEPENDENTFIRST INLET AND FIRST CONDUIT BELOW SAID COMBUSTION ZONE FOR TEMPORARILYSUPPLYING AN OXYGENCONTAINING GAS TO SAID COMBUSTION ZONE, ANINDEPENDENT SECOND INLET CONDUIT ABOVE SAID COMBUSTION ZONE AND DOWNFROM THE TOP OF SAID RETORTING VESSEL EQUIPPED WITH A GAS DISTRIBUTINGMEANS ADAPTED TO DISPERSE AN OXYGENCONTAINING GAS UNIFORMLY OVER THECROSS-SECTION OF THE MASS OF SOLIDS IN A DOWNWARDLY DIRECTION ACROSSSAID COMBUSTION ZONE WHEN SAID TEMPORARY SUPPLY OF OXYGEN-CONTAINING GASIS DISCONTINUED THROUGH SAID FIRST INLET CONDUIT, SAID FIRST OUTLETCONDUIT FOR WITHDRAWING A STREAM OF COMBUSTION PRODUCTS AND EDUCTED OILPRODUCTS FROM SAID RETORTING VESSEL, THE HEIGHT OF THE TOP OF SAIDRETORTING VESSEL ABOVE SAID SECOND INLET CONDUIT BEING MAINTAINED ATSEVERAL TIMES THE DISTANCE BETWEEN SAID SECOND INLET CONDUIT AND SAIDFIRST INLET AND FIRST OUTLET CONDUIT AN INDEPENDENT THIRD INLET CONDUITBELOW SAID FIRST OUTLET CONDUIT FOR INTRODUCING WATER INTO THE LOWERREGIONS OF SAID RETORTING VESSEL UNIFORMLY OVER THE CROSS-SECTION OF THEMASS OF SOLIDS TO COOL OIL-FREE SOLIDS AFTER COMBUSTION THEREOF, AND ANINDEPENDENT SECOND OUTLET CONDUIT IN THE BOTTOM OF SAID RETORTING VESSELFOR REMOVING SAID OIL-FREE SOLIDS THEREFROM.